Emergency breathing apparatuses that provide oxygen to the user are known. Some provide oxygen directly, such as those that use compressed or liquid oxygen. Others provide oxygen through a chemical reaction. Conventional chemical oxygen generators may contain alkali metal chlorate candles, which are burned to produce oxygen. Other conventional chemical oxygen generators may contain potassium superoxide, which reacts with carbon dioxide to produce oxygen.
For example, U.S. Pat. No. 5,690,099 discloses a closed-circuit breathing system that includes a mask and a canister containing, for example, KO2. The canister contains one or more working compounds formed of a peroxide and/or superoxide of one or more metals of the alkali and alkaline-earth metal groups, such as KO2 and CaO2, and a moisture releasing material, such as wetted activated charcoal, is used to replenish the oxygen and absorb the carbon dioxide in exhaled air. The canister includes an inlet port for receiving exhaled air, and an outlet port for providing breathable air for inhalation. The patent describes that the canister can be used in a closed or semi-closed circuit breathing system worn by a user such as a fireman, miner, etc.
U.S. Pat. No. 3,938,512 discloses an emergency breathing apparatus that includes a mask having a breathing opening, directly in front of the outer end of which there is a chemical cartridge that is secured to the mask. The cartridge has an exhalation passage extending through it from front to back, with its rear end registering with the breathing opening. A check valve in the inhalation passage allows air flow only into the mask. In the exhalation passage there is a carbon dioxide removing and oxygen generating chemical. A breathing bag is supported by the cartridge and communicates with the front end of the exhalation passage. The mask is provided with an inhalation check valve allowing air being inhaled from the bag to bypass the chemical.
U.S. Pat. No. 5,267,558 discloses a chemical cartridge for respirators, the cartridge containing a chemical, e.g., potassium hyperoxide, which when acted upon by carbon dioxide and moisture, produces oxygen from a stream of inhaled air. Two discharge nozzles are provided that project into the chemical and out of which the regenerated exhaled air flows. The incoming flow occurs over a large area and the outflow occurs over a small area with the peripheral surfaces of the discharge nozzles being spaced substantially equidistant from an inlet surface of the chemical, thereby ensuring optimum use of the chemical for oxygen production purposes because a user's exhaled air is caused to flow completely through the entire space occupied by the chemical.
U.S. Pat. No. 3,942,524 discloses an emergency breathing apparatus that includes a canister containing layers of KO2 particles separated by parallel screen assemblies, the upper two screen assemblies being connected by a vertical bypass screen near the canister inlet. The layered KO2 bed removes CO2 from exhaled breath, and generates oxygen for recharging the air prior to inhalation. The canister inlet is connected by a flexible hose to the exhalation side of a breather mouthpiece, the inhalation side of the mouthpiece being connected to the upper end of the inhalation chimney. Communication between the canister outlet and the lower end of the inhalation chimney is provided by a breather bag, fitted with a set of baffles to define a tortuous flow path for cooling the processed air. A collector mounted at the canister outlet prevents liquid KO2 (which forms KOH) from entering the breather bag. To protect the user and confine the heat within the canister, the canister is insulated.
U.S. Pat. No. 3,860,396 discloses a light-weight, portable oxygen generator containing an alkali metal chlorate candle. The generator includes a generally tubular housing, preferably formed of extruded aluminum or other heat-conducting metal, and preferably includes longitudinally-extending ribs which serve to dissipate heat generated inside of the housing. The generator also includes a dispensing valve through which oxygen passes.
U.S. Pat. No. 4,325,364 discloses a training breathing apparatus that includes a disposable canister filled with a reagent that creates heat by reacting with the moisture in exhaled breath.
U.S. Pat. No. 5,620,664 discloses a light-weight, personal, portable oxygen dispenser that includes a cylindrical body. The cylindrical body is a light-weight material, such as extrudable aluminum, with a fluted or ridged exterior configuration to minimize heat conductivity to the fingers of someone holding the dispenser while it is operating.
U.S. Pat. No. 7,513,251 discloses a potassium superoxide oxygen apparatuses in which the oxygen reaction is slowed down to decrease heat generation, thereby allowing the apparatus to be hand-held. Such hand-held generators may be used by, for example, people escaping fires, skiers, mountain climbers, asthmatics, people with emphysema, people suffering from altitude sickness, and athletes. Such hand-held generators may be also used as backup oxygen generators for Emergency Medical Service (EMS) squads, fire departments, miners, and the like, should their regular emergency oxygen become depleted.
U.S. Pat. No. 8,919,340 discloses a potassium superoxide oxygen apparatus comprising a filter that prevents particles having a diameter of 10 μm from passing through the filter, and neutralizes KOH and KO2 particles having a diameter of less than 10 μm that contact the filter into a food grade compound.